U.S. patent number 5,650,385 [Application Number 08/609,895] was granted by the patent office on 1997-07-22 for aqueous metal cleaner.
This patent grant is currently assigned to Church & Dwight Co., Inc.. Invention is credited to Steven Dunn, Anthony Winston.
United States Patent |
5,650,385 |
Dunn , et al. |
July 22, 1997 |
Aqueous metal cleaner
Abstract
A metal cleaning composition useful in aqueous solution
comprises an alkalinity providing agent and a combination of
surfactants comprising an ethoxylated thiol surfactant and a
nitrogen-containing surfactant which reduces the odor of the
thiol-containing surfactant. The aqueous cleaning solutions of this
invention are particularly useful in metal parts washers typically
placed in garages, service stations and the like in which the
cleaning solution can be filtered and reused in the parts
washer.
Inventors: |
Dunn; Steven (Hillsborough,
NJ), Winston; Anthony (East Brunswick, NJ) |
Assignee: |
Church & Dwight Co., Inc.
(Princeton, NJ)
|
Family
ID: |
23206101 |
Appl.
No.: |
08/609,895 |
Filed: |
March 4, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
311254 |
Sep 23, 1994 |
|
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Current U.S.
Class: |
510/245; 510/254;
510/421; 510/422; 510/423; 510/433; 510/475; 510/492; 510/500;
510/509 |
Current CPC
Class: |
C11D
1/002 (20130101); C11D 1/835 (20130101); C11D
3/046 (20130101); C11D 3/10 (20130101); C11D
3/28 (20130101); C11D 3/43 (20130101); C11D
11/0029 (20130101); C23G 1/14 (20130101); C23G
1/16 (20130101); C23G 1/19 (20130101); C23G
1/20 (20130101); C23G 1/24 (20130101); C11D
1/44 (20130101); C11D 1/526 (20130101); C11D
1/58 (20130101) |
Current International
Class: |
C11D
1/835 (20060101); C11D 3/28 (20060101); C23G
1/00 (20060101); C23G 1/19 (20060101); C11D
3/10 (20060101); C23G 1/14 (20060101); C23G
1/16 (20060101); C11D 3/02 (20060101); C23G
1/20 (20060101); C11D 3/26 (20060101); C23G
1/24 (20060101); C11D 11/00 (20060101); C11D
3/43 (20060101); C11D 1/00 (20060101); C11D
1/58 (20060101); C11D 1/44 (20060101); C11D
1/52 (20060101); C11D 1/38 (20060101); C11D
001/66 (); C11D 001/825 () |
Field of
Search: |
;510/245,254,421,422,423,433,475,500,509,492 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tierney; Michael
Attorney, Agent or Firm: Fishman; Irving M.
Parent Case Text
This application is a continuation, of application Ser. No.
08/311,254, filed Sep. 23, 1994 now abandoned.
Claims
What is claimed is:
1. An aqueous metal cleaning composition having excellent
metal-cleaning properties and reduced thiol-emitted malodor,
comprising 20-80 dry weight percent of an alkalinity providing
agent and cleaning effective amount of a mixture of surfactants
comprising an alkoxylated thiol surfactant and an N-alkyl
pyrrolidone surfactant having an alkyl group comprising 6-15 carbon
atoms, the N-alkylpyrrolidone surfactant being present in
sufficient amounts to reduce malodor of said alkoxylated thiol
surfactant, wherein said alkoxylated thiol surfactant is present in
said composition in amounts relative to said N-alkylpyrrolidone
surfactant of from about 1.0:0.1 to 1.0:2.0 based on he weight of
the respective surfactants, further wherein said metal cleaning
composition has a pH in water of greater than 8 and less than
12.
2. The metal cleaning composition of claim 1 wherein said
alkoxylated thiol surfactant comprises the reaction product of a
primary, secondary or tertiary alkyl thiol wherein said alkyl has
6-30 carbon atoms with ethylene oxide, said alkoxylated thiol
surfactant comprising 3-20 ethylene oxide groups.
3. The metal cleaning composition of claim 2 wherein said
alkoxylated thiol has 7-20 carbon atoms and is ethoxylated with
3-15 ethylene oxide units.
4. The metal cleaning composition of claim 1 wherein the amount of
alkoxylated thiol surfactant to said N-alkyl pyrrolidone surfactant
is from about 1.0:0.2 to 1.0:1.0 based on the weight of the
respective surfactants.
5. The metal cleaning composition of claim 1 wherein said N-alkyl
pyrrolidone is an N-(n-alkyl)-2 pyrrolidone.
6. The metal cleaning composition of claim 1 wherein said
alkalinity providing agent comprises alkali metal carbonates,
alkali metal bicarbonates or mixtures thereof.
7. The metal cleaning composition of claim 6 wherein said
alkalinity providing agent comprises a mixture of alkali metal
carbonates and alkali metal bicarbonates.
8. The metal cleaning composition of claim 1 further including a
polycarboxylate.
9. The metal cleaning composition of claim 1 further including a
hydrotrope.
10. The metal cleaning composition of claim 1 comprising 4-50 dry
weight percent of said alkoxylated thiol surfactant, 1-30 dry
weight percent of said N-alkyl pyrrolidone surfactant, 0-10 dry
weight percent of a polycarboxylate and 0-30 dry weight percent of
a hydrotrope.
11. The metal cleaning composition of claim 10 wherein said
alkalinity providing agent comprises alkali metal carbonate, alkali
metal bicarbonate or mixtures thereof and said alkoxylated thiol
surfactant comprises an ethoxylated alkyl thiol.
12. An aqueous metal cleaning solution having excellent
metal-cleaning properties and reduced thiol-emitted malodor,
comprising about 0.1-20 weight percent of a metal cleaning
composition an the balance water, said metal cleaning composition
comprising 20-80 dry weight percent of an alkalinity providing
agent and a cleaning effective amount of a mixture of surfactants
comprising an alkoxylated thiol surfactant and an N-alkyl
pyrrolidone surfactant having an alkyl group comprising 6-15 carbon
atoms, the N-alkylpyrrolidone surfactant being present in
sufficient amounts to reduce malodor of said alkoxylated thiol
surfactant, wherein said alkoxylated thiol surfactant is present in
said composition in amounts relative to said N-alkylpyrrolidone
surfactant of from about 1.0:0.1 to 1.0:2.0 based on weight of the
respective surfactants, said solution having a pH greater than 8
and less than 12.
13. The metal cleaning solution of claim 12 wherein said metal
cleaning composition comprises 4-50 dry weight percent of said
alkoxylated thiol surfactant, 1-30 dry weight percent of said
N-alkyl pyrrolidone surfactant, 0-10 dry weight percent of a
polycarboxylate and 0-30 dry weight percent of a hydrotrope.
14. The metal cleaning solution of claim 13 wherein said alkalinity
providing agent comprises alkali metal carbonate, alkali metal
bicarbonate or mixtures thereof.
15. The metal cleaning solution of claim 14 wherein said
alkoxylated thiol comprises an ethoxylated alkyl thiol having 7-20
carbon atoms and is ethoxylated with 3-15 ethylene oxide units.
16. The metal cleaning solution of claim 12 wherein said N-alkyl
pyrrolidone is an N-(n-alkyl)-2 pyrrolidone.
17. The metal cleaning solution of claim 12 wherein said alkalinity
providing agent comprises a mixture of alkali metal carbonates and
alkali metal bicarbonates.
18. An aqueous metal cleaning concentrate having excellent
metal-cleaning properties an reduced thiol-emitted malodor,
comprising 5-45 weight percent of a metal cleaning composition and
the balance water, said metal cleaning composition comprising 20-80
dry weight percent of an alkalinity providing agent and a cleaning
effective amount of mixture of surfactants comprising an alkoxylate
thiol surfactant and an N-alkylpyrrolidone surfactant having an
alkyl group comprising 6-15 carbon atoms, the N-alkylpyrrolidone
surfactant being present in sufficient amounts to reduce malodor of
said alkoxylated thiol surfactant, wherein said alkoxylated thiol
surfactant is present in said composition in amounts relative to
said N-alkylpyrrolidone surfactant of from about 1.0:0.1 to 1.0:2.0
based on weight of the respective surfactants, further wherein said
metal cleaning concentrate has a pH of greater than 8 and less than
12.
19. The aqueous cleaning concentrate of claim 18 wherein said metal
cleaning composition comprises 4-50 dry weight percent of said
alkoxylated thiol surfactant, 1-30 dry weight percent of said
N-alkyl pyrrolidone surfactant, 0-10 dry weight percent of a
polycarboxylate and 0-30 dry weight percent of a hydrotrope.
20. The aqueous cleaning concentrate of claim 19 wherein said
alkalinity providing agent comprises alkali metal carbonate, alkali
metal bicarbonate or mixtures thereof.
21. The aqueous cleaning concentrate of claim 20 wherein said
alkoxylated thiol comprises an ethoxylated alkyl thiol having 7-20
carbon atoms and is ethoxylated with 3-15 ethylene oxide units.
22. The metal cleaning solution of claim 18 wherein said N-alkyl
pyrrolidone is an N-(n-alkyl)-2 pyrrolidone.
23. The aqueous cleaning concentrate of claim 18 wherein said
alkalinity providing agent comprises a mixture of alkali metal
carbonates and alkali metal bicarbonates.
24. A method of cleaning a metal substrate so as to remove
contaminants therefrom comprising contacting said metal substrate
with an aqueous cleaning solution comprising the metal cleaning
composition of claim 1 in water, wherein said metal substrate is
contacted with said aqueous cleaning solution for a sufficient time
to remove said contaminants from said substrate.
25. The method of cleaning metal substrates of claim 24 wherein
said metal cleaning composition comprises 4-50 dry weigh percent of
said alkoxylated thiol surfactant, 1-30 weight percent of said
N-alkyl pyrrolidone surfactant, 0-10 weight percent of a
polycarboxylate and 0-30 dry weight percent of a hydrotrope.
26. The method of cleaning metal substrates of claim 25 wherein
said alkalinity providing agent comprises alkali metal carbonate,
alkali metal bicarbonate or mixtures thereof.
27. The method of cleaning metal substrates of claim 26 wherein
said alkoxylated thiol comprises an ethoxylated alkyl' thiol having
7-20 carbon atoms and is ethoxylated with 3-15 ethylene oxide
units.
28. The method of cleaning metal substrates of claim 24 wherein
said alkalinity providing agent comprises a mixture of alkali metal
carbonates and alkali metal bicarbonates.
29. The method of claim 24 wherein said aqueous cleaning solution
contains 0.1-20 weight percent of said metal cleaning composition
and has a pH of greater than 8 and less than 12.
30. The method of claim 29 wherein said aqueous cleaning solution
has a pH from about 8 to about 10.
31. The method of claim 24 wherein said metal substrates comprise
metal parts and wherein said metal parts are contacted with said
aqueous cleaning solution in a metal parts washer by immersion,
impingement or both, said metal parts separated from said cleaning
solution and said aqueous cleaning solution is reused in said parts
washer to clean additional parts.
32. The method of claim 31 wherein said metal parts are sprayed
with said aqueous cleaning solution.
33. The method of claim 32 wherein said aqueous cleaning solution
is at a temperature of from about 90.degree. -180.degree. F. and
said metal parts are contacted with said aqueous cleaning solution
for about 1-30 minutes.
34. A surfactant composition comprising an alkoxylated thiol
surfactant which has a malodor and an N-alkyl pyrrolidone
surfactant in amounts sufficient to reduce the malodor of said
alkoxylated thiol surfactant, wherein said alkoxylated thiol
surfactant is present in said composition in amounts relative to
said N-alkyl pyrrolidone surfactant of from about 1.0:0.1 to
1.0:2.0 based on the weight of the respective surfactants, further
wherein said N-alkyl pyrrolidone surfactant has an alkyl group
comprising 6-15 carbon atoms.
35. The surfactant composition of claim 34 wherein said alkoxylated
thiol surfactant comprises the reaction product of a primary,
secondary or tertiary alkyl thiol wherein said alkyl has 6-30
carbon atoms with ethylene oxide, said alkoxylated thiol surfactant
comprising 3-20 ethylene oxide groups.
36. The surfactant composition of claim 35 wherein said alkoxylated
thiol has 7-20 carbon atoms and is ethoxylated with 3-15 ethylene
oxide units.
37. The surfactant composition of claim 34 wherein the amount of
alkoxylated thiol surfactant to said N-alkyl pyrrolidone surfactant
is from about 1.0:0.2 to 1.0:1.0 based on the weight of the
respective surfactants.
38. The surfactant composition of claim 34 wherein said N-alkyl
pyrrolidone is an N-(n-alkyl)-2 pyrrolidone.
39. The metal cleaning composition of claim 1, wherein said metal
cleaning composition is free of organic solvents.
40. The metal cleaning solution of claim 12, wherein said metal
cleaning solution is free of organic solvents.
41. The aqueous cleaning concentrate of claim 18, wherein said
aqueous cleaning concentrate is free of organic solvents.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to aqueous metal cleaning
compositions. In particular, this invention is directed to aqueous
metal cleaning compositions useful in so-called parts washers and,
in particular, to parts cleaners, which are particularly adapted to
be used by professional or semi-professional mechanics, as well as
homeowners, farmers, ranchers, hobbyists, or other such users.
Parts washers of various kinds are known to those skilled in the
art as having great utility for mechanics and others working in a
variety of occupations, particularly those working in industrial
plants, maintenance and repair services, and the like. At one time,
the development of parts washers was based on an attempt to insure
reasonable convenience in use and good cleaning action. Many
garages, service stations and the like owned and used soak tanks,
so-called hot tanks, or immersion type parts cleaners, usually of
more or less elaborate configuration.
U.S. Pat. No. 3,522,814 to Olson and assigned to Safety-Kleen Corp.
described a new concept in parts washers insofar as it related to a
parts washer construction which included among other novel
features, a construction particularly adapted to facilitate
extremely rapid and simple machine service. An entire industry was
then founded on the concept of a parts washer which was designed so
that it could be economically and effectively serviced by route men
with little, if any, specialized training. It was discovered that
there was an enormous market among garage and service station
owners, automobile dealers, and industrial plant operators for a
parts washer which could be serviced safely and without disrupting
operations, either by way of downtime or physically interfering
with such operations.
The ideal parts washer is reliable, safe, quiet and effective in
use, is free from environmental objections, and perhaps most
importantly, can be serviced readily as just discussed. While the
parts washer described in U.S. Pat. No. 3,522,814 has achieved
phenomenal success in commercial markets, various improvements have
been made and are disclosed in several U.S. patent including; U.S.
Pat. No. 4,096,873; U.S. Pat. No. 4,160,603; U.S. Pat. No.
4,261,378; U.S. Pat. No. 4,462,415 and U.S. Pat No. 4,637,413.
The device described in the foregoing patent to Olson has been
extremely successful in the industry by providing a parts washer
having economic and hazard-free operation to subject parts to be
cleaned to a circulating flow of solvent and the like. In operation
of the device described in the Olson patent, a pump circulates a
solvent from a drum into a sink containing parts for cleaning. A
flow of solvent is directed against the parts and drains from the
sink through a filtering medium for return to the drum. In the
event of a fire, the washer described in U.S. Pat. No. 3,522,814 is
capable of automatically closing a cover over the sink to minimize
its effect.
Although the washer of U.S. Pat. No. 3,522,814 provides highly
improved operative characteristics during cleaning, it has been
found that it becomes advantageous to subject parts for a period of
time to a soaking bath in a solvent or other fluid under certain
encountered conditions such as, for example, where an extraordinary
amount of foreign material is affixed to the elements to be washed.
In known techniques, such soaking is accomplished generally by
positioning the parts in a volume of fluid in an opened container
from which undesired solvent fumes may be evaporated to the
surroundings with a resulting costly depletion of fluid and the
danger of uncontrolled fire or spilling being present. The
prevention of such uncontrolled soaking in an open vessel has
become more advantageous in the light of numerous government
regulations governing the use of substances in the form of solvents
such as required by O.S.H.A. and the like. Thus, U.S. Pat. No.
4,261,378 mentioned above, provides a highly advantageous accessory
which allows effective washing of parts with drainage such as
disclosed in U.S. Pat. No. 3,522,814, with the alternative mode of
operation as a highly effective and non-hazardous soaking
device.
The accessory disclosed in U.S. Pat. No. 4,261,378 overcomes the
foregoing problems by permitting a conventional washer to operate
in its normal circulating mode without a substantial soaking
action, with the added improvement of selectively retaining a
quantity of solvent in a sink for a soaking application. The
soaking operation provided by the accessory is accomplished by a
device which prevents the escape of fumes to the surroundings and
the costly evaporation of the cleaning solvent, and which at the
same time minimizes the danger of fire and other accidents. In
addition, the accessory provides improved soaking by maintaining a
predetermined level of fluid over the parts to be cleaned with
constant circulation of the solvent. U.S. Pat. No. 4,261,378 is
herein incorporated by reference.
Existing solvents, with or without special additives, are adequate
to achieve good cleaning of most dirty, greasy, mechanical parts. A
great number of these solvents are employed to produce metallic
surfaces free from contamination. These wash solvent compositions
generally employ various halogenated hydrocarbons and
non-halogenated hydrocarbons, of significant quantity industry wide
for cleaning and degreasing of the metal surfaces, and the degree
of success with each of these wash solvent compositions is
generally dependent upon the degree of cleanliness required of the
resultant surface.
Recently, however, the various hydrocarbon and halogenated
hydrocarbon metal cleaning compositions previously employed have
come under scrutiny in view of the materials employed, and in
particular, the environmental impact from the usage of the various
materials. This is particularly so in the case of parts cleaning
which is done in closed environments such as garages and the like
or for even home usage in view of the close human contact. Even the
addition of devices to parts washers which can reduce spillage,
fire and excessive volatilization of the cleaning solvent are not
sufficient to alleviate present environmental concerns.
Although the halogenated hydrocarbon solvents such as
chlorofluorocarbons (CFCs) and trichloromethane, methylene chloride
and trichloroethane (methyl chloroform) are widely used in industry
for metal cleaning, their safety, environmental and cost factors
coupled with waste disposal problems are negative aspects in their
usage. A world-wide and U.S. ban on most halogenated hydrocarbon
solvents is soon in the offing by virtue of the Montreal Protocol,
Clean Air Act and Executive and Departmental directives.
The non-halogenated hydrocarbon solvents such as toluene and
Stoddard solvent and like organic compounds such as ketones and
alcohols on the other hand are generally flammable, have high
volatility and dubious ability to be recycled for continuous use.
These, plus unfavorable safety, environmental and cost factors, put
this group of solvents in a category which is unattractive for
practical consideration. Most useful organic solvents are
classified as volatile organic compounds (VOCs) which pollute the
atmosphere, promote formation of toxic ozone at ground level, and
add to the inventory of greenhouse gases.
In order to eliminate the various negative aspects of the known
chemical washing and degreasing systems, it has, therefore, been
suggested that an aqueous detergent system be used so as to
overcome some of the inherent negative environmental and health
aspects of prior art solvent cleaning systems. Unfortunately,
aqueous cleaning systems are not without their own problems as
related to used thereof in metal cleaning systems including use in
the parts washers described above. For example, certain of the
aqueous cleaners are exceedingly alkaline having pHs of 13 and
above such as sodium hydroxide or include organic solvents such as
alkanolamine, ethers, alcohols or glycols and the like. Besides
being highly corrosive, the exceedingly high alkaline aqueous
solutions are highly toxic and can be dangerous to handle requiring
extreme safety measures to avoid contact with skin. Organic
solvent-containing aqueous cleaners present the problems regarding
toxicity or the environment as expressed previously. On the other
hand, it is most difficult to obtain an aqueous detersive solution
at moderate pH which is effective in removing the greases and oils
which contaminate metal including metal engine parts and which
would not be corrosive to the metal substrate.
U.S. Pat. No. 5,230,824 discloses an aqueous metal cleaning
composition for removing oil, dirt and grinding debris from razor
blades and which comprises an alkalinity providing agent, a
chelating agent, a hydrotrope and a defoaming agent together with a
non-ionic surfactant. The preferred alkalinity providing agents
include the alkali metal hydroxides, the alkali metal silicates and
the alkali metal carbonates. The non-ionic surfactant comprises the
ethoxylates of C.sub.9 -C.sub.16 tertiary thiols as described in
U.S. Pat. Nos. 4,575,569 and 4,931,205.
While the ethoxylated thiol surfactants have been found to be
highly effective in aqueous solution for the removal of grease from
substrates, particularly metal surfaces, one drawback of these
surfactants is the very unpleasant odor which the surfactant
imparts to the product such as an aqueous concentrate to which the
surfactants are added as well as to the more dilute wash solutions
which contain these ethoxylated thiol surfactants. The unpleasant
odor significantly reduces the types of product to which the
ethoxylated thiols can be added. This would be particularly so of
the parts washing systems such as described above and developed by
Safety-Kleen Corp. which have been very successful in the
commercial service area including garage and service stations,
automobile dealers and the like. In the typical enclosed
environments which such commercial enterprises operate, the
unpleasant odor of the ethoxylated thiol surfactants would not be
tolerated and the use thereof would greatly hinder the commercial
operation. On the other hand, the excellent grease removing ability
of these surfactants render them most useful in aqueous cleaning
systems for parts washing devices and methods of metal
cleaning.
Accordingly, it is an object of the present invention to provide an
aqueous metal cleaning composition which is effective to clean
grease, oil and other contaminants from a metal surface without
being excessively corrosive to the substrate and irritating to
human skin.
Another object of the invention is to provide an aqueous metal
cleaning composition which can be used effectively in immersion and
impingement type parts washers so as to efficiently remove grease,
oil and other contaminants from metal parts and which are safe to
use and not a hazard to the environment in use or upon
disposal.
Still another object of the present invention is to provide an
aqueous metal cleaning composition which contains an ethoxylated
thiol surfactant and which is formulated so as to greatly reduce if
not eliminate the unpleasant odor associated with the
surfactant.
Yet another object of the present invention is to provide an
aqueous cleaning composition containing an ethoxylated thiol
surfactant and which does not have the unpleasant odor associated
with the surfactant and, thus, can be effectively used in immersion
and impingement type parts washers and in the relatively closed
commercial settings in which such parts washers are utilized.
SUMMARY OF THE INVENTION
The above-mentioned objectives and other objects are obtained in
accordance with the present invention by providing an aqueous
alkaline metal cleaning solution which has a pH of less than 12 but
a sufficiently high pH to effectively clean dirt, grease, oil and
the like from metal and which includes an ethoxylated thiol
surfactant which greatly enhances the detersive ability of the
aqueous alkaline solution but does not impart an unpleasant odor
thereto. Unlike the halogenated or hydrocarbon solvents of the
prior art, the aqueous alkaline solution of this invention is
environmentally safe in use having only low amounts of organics
which do not readily volatilize and which is safe on disposal
thereof.
The aqueous metal cleaning composition of the present invention
comprises an alkalinity providing agent and a combination of
surfactants comprising an ethoxylated thiol and a
nitrogen-containing surfactant which greatly reduces if not
eliminates the unpleasant odor associated with the ethoxylated
thiol surfactant. The nitrogen-containing surfactant does not
reduce the efficacy of the ethoxylated thiol relative to the
ability to cut grease from the metal substrate. Moreover, the
cleaning composition of this invention does not readily emulsify
the oil and grease which is removed from the metal surface so as to
allow such grease and oil to be skimmed or otherwise easily
separated from the wash bath for disposal. Consequently, the
cleaning ability of the aqueous cleaner can be maintained for
prolonged reuse.
The aqueous cleaning composition of this invention is particularly
effective when used in the parts washing systems such as those
developed by Safety-Kleen Corporation and the like which have
become enormously successful commercially, whether controlled
manually or of automatic type. The cleaning composition and aqueous
cleaning solutions formed therefrom are especially useful in
washing systems situated in relatively closed commercial quarters
such as gas stations, garages and the like. The aqueous metal
cleaning compositions of this invention for use in such parts
washing systems are particularly advantageous since such
compositions are environmentally and physically safe to use in
relatively closed environments and can be handled, stored and
disposed of without the environmental problems caused by volatile
and toxic organics or the hazards of extremely high alkaline
aqueous compositions which have been previously suggested.
BRIEF DESCRIPTION OF THE DRAWING
The Figure is a graph of cleaning efficacy comparing the inventive
formulation with known commercial cleaners.
DETAILED DESCRIPTION OF THE INVENTION
The aqueous cleaning compositions of the present invention comprise
an alkalinity providing agent and a combination of two surfactants,
one being an ethoxylated thiol which is very effective in removing
grease and oil from metal substrates and a nitrogen-containing
surfactant which surprisingly greatly reduces the odor associated
with the ethoxylated thiol surfactant and does not reduce the
efficacy of the ethoxylated thiol surfactant. The aqueous alkaline
metal cleaning solutions have a pH of at least 8.0 to less than 12,
preferably less than 11.0 so as to render these solutions
substantially less harmful to use and handle than highly alkaline
aqueous cleaners such as those formed from sodium hydroxide or
aqueous alkanol amine solutions. Most preferably, the aqueous
alkaline cleaning solutions have a pH from about 8.0 to 10.0 which
is effective to remove the dirt, grease, oil and other contaminants
from the metal surface and yet allow the solutions to be used,
handled and disposed of without burning or irritating human skin.
Also, it is preferable that the composition of this invention be
free of organic solvents, including hydrocarbon, halohydrocarbon
and oxygenated hydrocarbon solvents.
The alkalinity providing agent of the aqueous metal cleaning
compositions of the present invention can be provided by one or
more alkaline salts. Suitable alkaline salts or mixtures thereof
useful in the present invention are those capable of providing the
desired pH. Most suitable are the salts of potassium and sodium.
Especially preferred are the potassium and sodium carbonates and
bicarbonates which are economical, safe and environmentally
friendly. The carbonate salts include potassium carbonate,
potassium carbonate dihydrate, potassium carbonate trihydrate,
sodium carbonate, sodium carbonate decahydrate, sodium carbonate
heptahydrate, sodium carbonate monohydrate, sodium sesquicarbonate
and the double salts and mixtures thereof. The bicarbonate salts
include potassium bicarbonate and sodium bicarbonate and mixtures
thereof. Mixtures of the carbonate and bicarbonate salts are also
especially useful.
Although not preferred, other suitable alkaline salts which can be
used include the alkali metal ortho or complex phosphates. The
complex phosphates are especially effective because of their
ability to chelate water hardness and heavy metal ions. The complex
phosphates include, for example, sodium or potassium pyrophosphate,
tripolyphosphate and hexametaphosphates. Additional suitable
alkaline salts useful in the metal cleaning compositions of this
invention include the alkali metal borates, acetates, citrates,
tartrates, succinates, silicates, phosphonates, edates, etc.
The alkoxylated (ethoxylated) thiol surfactants of the present
invention are known nonionic surfactants and are described for
example in U.S. Pat. Nos. 4, 575,569 and 4,931,205, the contents of
both of which are herein incorporated by reference. In particular,
the ethoxylated thiol is prepared by the addition of ethylene oxide
to an alkyl thiol of the formula R--SH wherein R is alkyl in the
presence of either an acid or base catalyst.
The thiol reactant that is suitable for producing the surfactant
used in the practice of the present invention comprises, in the
broad sense, one or more of the alkane thiols as have heretofore
been recognized as suitable for alkoxylation by reaction with
alkylene oxides in the presence of basic catalysts. Alkane thiols
in the 6 to 30 carbon number range are particularly preferred
reactants for the preparation of thiol alkoxylates for use as
surface active agents, while those in the 7 to 20 carbon number
range are considered more preferred and those in the 8 to 18 carbon
number range most preferred.
The thiol reactant molecule is suitably either primary, secondary,
or tertiary and of either linear, branched, or cyclic carbon
structure. Specific examples of suitable tertiary thiols are those
having a highly branched carbon chain which are derived via
hydrosulfurization of the products of the oligomerization of lower
olefins, particularly those dimers, trimers, and tetrameres and
pentamers of propylene and the butylenes. Secondary thiols are
exemplified by the lower alkane thiols, such as 2-propanethiol,
2-butanethiol, and 3-pentanethiol, as well as by the products of
the hydrosulfurization of the substantially linear oligomers of
ethylene as are produced by the Oxo process. Representative, but by
no means limiting, examples of thiols derived from ethylene
oligomers include the linear carbon chain products, such as
2-decanethiol, 3-decanethiol, 4-decanethiol, 5-decanethiol,
3-dodecanethiol, 5-dodecanethiol, 2-hexadecanethiol,
5-hexadecanethiol, and 8-octadecanethiol, and the branched carbon
chain products, such as 2-methyl-4-tridecanethiol. Primary thiols
are typically prepared from terminal olefins by hydrosulfurization
under free-radical conditions and include, for example,
1-butanethiol, 1-hexanethiol, 1-dodecanethiol, and
1-tetradecanethiol and 2-methyl-1-tridecanethiol. Polythiol
reactants, having multiple --SH groups, can be used although
monothiolic reactants are preferred. Particular preference exists
for a reactant consisting essentially of one or more secondary and
tertiary thiols.
Broadly, the surfactant can be formed from reaction of the above
alkyl thiol and one or more of the several alkylene oxides known
for use in alkoxylation reactions with thiols and other compounds
having active hydrogen atoms. Particularly preferred are the
vicinal alkylene oxides having from 2 to 4 carbon atoms, including
ethylene oxide, 1,2-propylene oxide, and the 1,2-and 2,3-butylene
oxides. Mixtures of alkylene oxides are suitable in which case the
product will be mixed thiol alkoxylate. Thiol alkoxylates prepared
from ethylene or propylene oxides are recognized to have very
advantageous surface active properties and for this reason there is
a particular preference for a reactant consisting essentially of
ethylene oxide which is considered most preferred for use in the
invention.
The relative quantity of thiol and alkylene oxide reactants
determine the average alkylene oxide number of the alkoxylate
product. In the alkoxylated thiol surfactant of this invention an
adduct number in the range from about 3 to 20, particularly from
about 3 to 15 is preferred. Accordingly, preference can be
expressed in the practice of the invention for a molar ratio of
alkylene oxide reactant to thiol reactant which is in the range
from about 3 to 20, particularly from about 3 to 15. Especially
preferred is an ethoxylated dodecyl mercaptan with about 6 ethylene
oxide units. Such a surfactant is a commercial product known as
ALCODET 260 marketed by Rhone-Poulenc.
Unfortunately, the ethoxylated thiol surfactant useful in the
aqueous cleaning compositions of this invention has an unpleasant
odor which is imparted to the aqueous solution in which it is
placed. It has now been found that the addition of a
nitrogen-containing surfactant eliminates the odor of the
sulfur-containing surfactant and does not adversely effect the
efficacy of the ethoxylated thiol surfactant to remove grease, oil
and the like from the metal surfaces. Among useful
nitrogen-containing nonionic surfactants are the following:
A surfactant having a formula R.sup.1 R.sup.2 R.sup.3 N.fwdarw.O
(amine oxide detergent) wherein R.sup.1 is an alkyl group
containing from about 10 to about 28 carbon atoms, from zero to
about two hydroxy groups and from zero to about five ether
linkages, there being at least one moiety of R.sup.1 which is an
alkyl group containing from about 10 to about 18 carbon atoms and
zero ether linkages, and each R.sup.2 and R.sup.3 are selected from
the group consisting of alkyl radicals and hydroxyalkyl radicals
containing from one to about three carbon atoms.
Specific examples of amine oxide surfactants include:
Dimethyldodecylamine oxide, dimethyltetradecylamine oxide;
ethylmethyltetradecylamine oxide, cetyldimethylamine oxide,
dimethylstearylamine oxide, cetylethylpropylamine oxide,
diethyldodecylamine oxide, diethyltetradecylamine oxide,
dipropyldodecylamine oxide, bis-(2-hydroxyethyl)dodecylamine oxide,
bis-(2-hydroxyethyl)-3-dodecoxy-1-hydroxypropyl amine oxide,
(2-hydroxypropyl)methyltetradecylamine oxide, dimethyloleyamine
oxide, dimethyl-(2-hydroxydodecyl)amine oxide, and the
corresponding decyl, hexadecyl and octadecyl homologs of the above
compounds.
Additional nitrogen-containing surfactants include ethoxylated
primary alkyl amines where the alkyl group has 10-20 carbon atoms
and the amine is ethoxylated with 2-20 ethylene oxide units.
Further surfactants include ethoxylated long chain fatty acid
amides where the fatty acid has 8-20 carbon atoms and the amide
group is ethoxylated with 1-20 ethylene oxide units. Additionally,
nonionic surfactants derived from the condensation of ethylene
oxide with the product resulting from the reaction of propylene
oxide and ethylene diamine are also useful. For example, compounds
containing from about 40% to about 80% of polyoxyethylene by weight
and having a molecular weight from about 5,000 to about 11,000
resulting from the reaction of ethylene oxide groups with a
hydrophobic base constituted of the reaction product from ethylene
diamine and excess propylene oxide wherein the base has a molecular
weight on order of 2,500-3,000 are satisfactory.
One of the most useful nitrogen-containing surfactants which can be
used in combination with the ethoxylated thiol surfactant are those
derived from N-alkyl pyrrolidone. Particularly preferred are
N-(n-alkyl)-2-pyrrolidone wherein the alkyl group contains 6-15
carbon atoms. These compounds are described in U.S. Pat. No.
5,093,031, assigned to ISP Investments, Inc., Wilmington, Del. and
which discloses surface active lactams and is herein incorporated
by reference. The above N-alkyl pyrrolidone products having a
molecular weight of from about 180 to about 450 are conveniently
prepared by several known processes including the reaction between
a lactone having the formula ##STR1## wherein n is an integer from
1 to 3, and an amine having the formula R'--NH.sub.2 wherein R' is
a linear alkyl group having 6 to 20 carbon atoms. The amine
reactant having the formula R'--NH.sub.2 includes alkylamines
having from 6 to 20 carbon atoms; amines derived from natural
products, such as coconut amines or tallow amines distilled cuts or
hydrogenated derivatives of such fatty amines. Also, mixtures of
amine reactants can be used in the process for preparing the
pyrrolidone compounds. Such mixtures can include linear amino
species having an alkyl of the same or different molecular weight.
To form the pyrrolidone, the amine and lactone reactants, combined
in a mole ration of from about 1:1 to about 1:5, are reacted under
conditions of constant agitation, at a temperature between about
100.degree. C. and about 350.degree. C. under a pressure of from
atmospheric to about 650 psig for a period of from about 1 to about
15 hours; preferably at 250.degree. C. to 300.degree. C. under an
initial ambient pressure for a period of from 5 to 10 hours. The
resulting pyrrolidone product is recovered and purified by
distillation or by any other convenient recovery process.
The N-alkyl pyrrolidone products having 11 to 14 carbon atoms are
clear, water white liquids, at room temperature; whereas those
having 16 or more carbon atoms are solids. These pyrrolidones have
a neutral or slightly basic pH, a surface tension between about 25
and about 35 dynes/cm as a 0.1% water solution and a viscosity of
from about 6 to about 30 cps at 25.degree. C.
Generally, the C.sub.6 to C.sub.14 alkyl pyrrolidones display
primarily surfactant properties; whereas the C.sub.16 to C.sub.22
alkyl species are primarily complexing agents; although some degree
of surfactant and complexing capability exists in all of the
present species. One particular advantage of the alkyl pyrrolidone
surfactants is the additional detergency that these surfactants
provide to the compositions of this invention.
U.S. Pat. No. 5,093,031 states that the inventive compounds control
objectionable odors emanating from metal treating and slaughter
house operations as well as household odors on rugs, furniture,
clothing or encountered in pet environments. The surfactants of the
patent are stated as being able to complex with odor forming bodies
in animal and human waste containing, for example, mercaptan, urea,
tars, nicotine, molds and other odor causing chemicals.
The relative amounts of the ethoxylated thiol surfactant and
nitrogen-containing surfactant are not overly critical as far as a
contrite range is concerned in that the amount of the nitrogen
surfactant will vary depending on the surfactant used. The amount
of nitrogen-containing surfactant used should be that which can
reduce if not eliminate the odor of the ethoxylated thiol
surfactant. In general, it is believed that the relative amounts by
weight of the ethoxylated thiol surfactant to the
nitrogen-containing surfactant should range from about 1.0:0.1 to
1.0:2.0, and preferably from about 1.0:0.2 to 1:1. It is not meant
that these ratios be considered as strictly limiting the invention
and as providing the only relative amounts of the respective
surfactants which can be effectively used and accordingly, it is
intended that any useful ratio be considered part of the present
invention. Any useful ratio is that ratio which is sufficient to
remove the dirt, grease, oil and other contaminants from the metal
surface and which will yield an aqueous product which has greatly
reduced malodor relative to an equivalent composition in which the
ethoxylated thiol surfactant is present and the nitrogen-containing
surfactant is not.
Besides the alkalinity providing agent and the surfactant
combination as described above, the aqueous metal cleaning
compositions of the present invention preferably include a
hydrotrope and a polycarboxylate which prevents precipitation of
water hardness salts. In use, the dry ingredients of the invention
are provided in solution in water which is preferably deionized or
purified by reverse osmosis treatment and the like.
The polymeric antiprecipitating agents may be generically
categorized as a water-soluble carboxylic acid polymer or a vinyl
addition polymer. Polyacrylates are especially preferred. Of the
vinyl addition polymers contemplated, maleic anhydride copolymers
as with vinyl acetate, styrene, ethylene, isobutylene, acrylic acid
and vinyl ethers are preferred.
All of the above-described polymers are water-soluble or at least
colloidally dispersible in water. The molecular weight of these
polymers may vary over a broad range although it is preferred to
use polymers having average molecular weights ranging between 1,000
up to 1,000,000. In a preferred embodiment of the invention, these
polymers have a molecular weight of 100,000 or less and, most
preferably, between 1,000 to 10,000. While higher molecular weight
polymers may be used, there is no particular advantage in their
utilization because they tend to be broken down due to the shear
forces found in recirculating cooling systems. Also, when used in
larger amounts in concentrated formulas, they produce highly
viscous products that are difficult to use.
The water-soluble polymers of the type described above are often in
the form of copolymers which are contemplated as being useful in
the practice of this invention provided they contain at least 10%
by weight of ##STR2## groups where M is hydrogen, alkali metal,
ammonium or other water-solubilizing radicals. The polymers or
copolymers may be prepared by either addition or hydrolytic
techniques. Thus, maleic anhydrided copolymers are prepared by the
addition polymerization of maleic anhydride and another comonomer
such as styrene. The low molecular weight acrylic acid polymers may
be prepared by addition polymerization of acrylic acid or its salts
either with itself or other vinyl comonomers. Alternatively, such
polymers may be prepared by the alkaline hydrolysis of low
molecular weight acrylonitrile homopolymers or copolymers. For such
a preparative technique see Newman U.S. Pat. No. 3,419,502.
As previously stated, maleic anhydride polymers are preferred.
Especially useful maleic anhydride polymers are selected from the
group consisting of homopolymers of maleic anhydride, and
copolymers of maleic anhydride with vinyl acetate, styrene,
ethylene, isobutylene, acrylic acid and vinyl ethers. These
polymers can be easily prepared according to standard methods of
polymerization.
The carboxylated polymer prevents scaling due to precipitation of
water hardness salts formed during reaction with the alkaline salts
of the cleaning compositions of this invention.
The hydrotropes useful in this invention include the sodium,
potassium, ammonium and alkanol ammonium salts of xylene, toluene,
ethylbenzoate, isopropylbenzene, naphthalene, alkyl naphthalene
sulfonates, phosphate esters of alkoxylated alkyl phenols,
phosphate esters of alkoxylated alcohols and sodium, potassium and
ammonium salts of the alkyl sarcosinates. The hydrotropes are
useful in maintaining the surfactant readily dispersed in the
aqueous cleaning solution and, in particular, in an aqueous
concentrate which is an especially preferred form of packaging the
compositions of the invention and allow the user of the
compositions to accurately provide the desired amount of cleaning
composition into the aqueous wash solution. A particularly
preferred hydrotrope is one that does not foam. Among the most
useful of such hydrotropes are those which comprise the alkali
metal salts of intermediate chain length monocarboxylic fatty
acids, i.e., C.sub.7 -C.sub.13. Particularly preferred are the
alkali metal octanoates and nonanoates.
The metal cleaning compositions of this invention comprise from
about 20 to 80 weight percent based on the dry components of the
alkalinity providing agent, 4 to 50 weight percent of the
ethoxylated thiol surfactant, 1-30 weight percent of the
nitrogen-containing surfactant, 0-10 weight percent of the
anti-scaling agent and 0-30 weight percent of the hydrotrope. If
the alkalinity providing agent is the preferred carbonate and
bicarbonate salts, the combination of such salts should be present
in the amounts of 20-80 percent by weight. Preferably, if such a
mixture is utilized the amount of bicarbonate salts should comprise
from about 5-80 weight percent and the carbonate salts from about
5-60 percent by weight based on the dry composition. The dry
composition is used in the aqueous wash solution in amounts of
about 0.1-20 weight percent, preferably from about 0.2-5 weight
percent. Most preferably, the metal cleaning compositions of the
present invention are provided and added to the wash bath as an
aqueous concentrate in which the dry components of the composition
comprise from about 5-45 weight percent of the concentrate and,
preferably, from about 5-20 weight percent.
The aqueous metal cleaning solutions of the present invention are
useful in removing a variety of contaminants from metal substrates.
In particular, metal substrates comprising engine parts which are
contaminated with grease and oil are advantageously cleaned using
the metal cleaning compositions of this invention and aqueous
solutions of such compositions. A useful method of cleaning such
metal parts is in a parts washer. In such parts washers the metal
parts are contacted with the aqueous solution either by immersion
or some type of impingement in which the aqueous cleaning solution
is circulated continuously on the metal part or is sprayed thereon.
Alternatively, agitation can be provided as ultrasonic waves. The
cleaning solution is then filtered and recycled for reuse in the
parts washer. For best use, the aqueous cleaning solutions of this
invention should be at an elevated temperature typically ranging
from about 90.degree. -180.degree. F. The contact time of the
aqueous cleaning solution with the metal substrates including metal
engine parts will vary depending upon the degree of contamination
but broadly will range between about 1 minute to 30 minutes with 3
minutes to 15 minutes being more typical.
The metal cleaning compositions of the present invention are useful
for removing any type of contaminant from a metal surface including
greases, cutting fluids, drawing fluids, machine oils, antirust
oils such as cosmoline, carbonaceous soils, sebaceous soils,
particulate matter, waxes, paraffins, used motor oil, fuels, etc.
Any metal surface can be cleaned including iron-based metals such
as iron, iron alloys, e.g., steel, tin, aluminum, copper, tungsten,
titanium, molybdenum, etc., for example. The structure of the metal
surface to be cleaned can vary widely and is unlimited. Thus, the
metal surface can be as a metal part of complex configuration,
sheeting, coils, rolls, bars, rods, plates, disks, etc. Such metal
components can be derived from any source including for home use,
for industrial use such as from the aerospace industry, automotive
industry, electronics industry, etc., wherein the metal surfaces
have to be cleaned.
EXAMPLE 1
The following panel test was run to determine whether or not
nitrogen-containing compounds would reduce the odor of a cleaning
formulation containing an ethoxylated thiol surfactant. Table 1
sets forth the formulation and control (without nitrogen-containing
compounds).
TABLE 1 ______________________________________ Samples A B
Ingredients wt % wt(g) wt. % wt(g)
______________________________________ 1 DI H2O 78.2 312.80 79.7
318.80 2 Sodium bicarbonate 7.36 29.44 7.36 29.44 3 Pot. carbonate
1.96 7.84 1.96 7.84 4 Sod. carbonate 1.60 6.40 1.60 6.4 5
Alcosperse 408.sup.1 0.38 1.52 0.38 1.52 6 Monatrope 1250.sup.2
6.00 24.00 6.00 24.00 7 Alcodet 260.sup.3 3.00 12.00 3.00 12.00 8
ISP LP-100.sup.4 1.50 6.00 -- -- TOTALS 100.00 400.00 100.00 400.00
pH 9.00 pH 9.00 ______________________________________ .sup.1
acrylic acid polymer, Alco Chemical Co., Chatanooga, TN .sup.2
sodium nonanoate, Mona Industries .sup.3 ethoxylated dodecyl
mercaptan (6 ethylene oxide units) .sup.4 Nalkyl pyrrolidone,
ISP
The odor panel protocol was as follows. Both solutions were
evaluated at room temperature for comparable objectionable odors. A
panel of 6 persons were requested to smell comparative formulation
Sample B and give it a 7 on a scale of 1-10. Subsequently, each
member of the panel was requested to smell formulation Sample A and
rate the odor of the solution on a scale of 1-10. Table 2 sets
forth the results.
TABLE 2 ______________________________________ Panel member 1 2 3 4
5 6 Scale Value 7-3 7-3.5 7-5 7-3 7-2 7-5 (B-A)
______________________________________
All six panel members picked the formulation of the present
invention (Sample A) as having less malodor than Comparative Sample
B.
A second test was conducted in which Samples A and B were diluted
(10X) with water and evaluated at 160.degree. F. In this odor panel
test, the comparative formulation Sample B was smelled and was
given a 5 on the scale of 1-10. The formulation Sample A was then
smelled and provided with a rating by each panel member. Table 3
sets for the results of the panel test.
TABLE 3 ______________________________________ Panel member 1 2 3 4
5 (Scale Value) 5-1 5-1 5-2 5-2.5 5-2
______________________________________
Again, all five of the panel members picked formulation Sample A as
having less malodor than Comparative Sample B.
EXAMPLE 2
In this example, further odor testing was done to determine whether
various nitrogen-containing compounds including the pyrrolidone
compound used in Example 1 and other nitrogen and non-nitrogen
containing compounds could reduce the malodor of a cleaning
composition containing the ethoxylated thiol surfactant.
Significant reduction of malodor was determined by using a
sequential analysis chart. Control Sample C had the formulation as
set forth in Table 4 below.
TABLE 4 ______________________________________ SAMPLE C Ingredients
Wt. % ______________________________________ DI H.sub.2 O 81.08
Sodium bicarbonate 4.48 Potassium carbonate 2.90 Sodium carbonate
2.22 Magnesium oxide 0.074 Carboxylate copolymer.sup.1 0.25
Monotrope 1250 6.00 Alcadet 260 3.00
______________________________________ .sup.1 Acrylic acid/maleic
acid copolymer, molecular weight 4,500.
Samples D-I had the same formulation as the control example except
that 1.50% of the water was replaced with the respective compound
being tested for malodor reduction. Table 5 summarizes the testing
of the six compounds D-I with respect to malodor reduction of the
control.
TABLE 5 ______________________________________ No. Panelists Sig.
Deodorizing Preferring Diff..sup.1 Av. Odor Sample compound Test
Control (95%) Test Control ______________________________________ D
LP-100 28 2 yes 3 5 E C.sub.18 amide.sup.2 14 2 yes 2.9 5 F
Acetamide 16 3 yes 3.7 5 G Ethoxylated amine.sup.3 8 0 yes 2.3 5 H
Polytergent CS-1.sup.4 12 12 no 4.8 5 I Nedol 1-9.sup.5 19 11 no
4.3 5 ______________________________________ .sup.1 The statistical
test applied was sequential analysis (Amitage, P., Sequential
Medial Trials, 2nd Ed., Blackwell, Oxford (1975) .sup.2 AKZO,
Ethomid 0/17 .sup.3 Witco, VARONIC K205 .sup.4 Olin,
polycarboxylated EO condensate of fatty alcohols .sup.5 Shell, 9EO
condensate of C.sub.11 alcohol
As can be seen, Samples D-G were able to significantly reduce the
malodor of the thioether-containing surfactant. Each of these
materials included a nitrogen group. On the other hand, the two
ethoxylated surfactants which do not contain the nitrogen group
were unable to significantly reduce the malodor of the thioether
surfactant.
EXAMPLE 3
In this Example, an aqueous cleaning formulation within the scope
of the present invention was tested for cleaning ability and
compared with the cleaning ability of two commercial cleaners and a
control which had the equivalent alkalinity of the inventive
formulation but did not include the surfactant or other active
ingredients. Table 6 sets forth Sample J, the cleaner of the
present invention.
The commercial cleaners were Brulin 815 GD.RTM., a phosphate-based
cleaner containing a high level of surfactant and Daraclean
235.RTM. (W. R. Grace) which contains triethanolamine.
TABLE 6 ______________________________________ SAMPLE J wt %
______________________________________ Deionized water 81.910
Sodium bicarbonate 4.480 Potassium carbonate 2.900 Sodium carbonate
2.220 Magnesium oxide 0.074 BJ 76.sup.1 0.250 Sodium nonanoate
3.000 Alcodet 260 3.000 LP 100 1.500
______________________________________ .sup.1 A polycarboxylated
copolymer containing acrylic and maleic acid units and having a
molecular weight of about 4,500.
1. A polycarboxylated copolymer containing acrylic and maleic acid
units and having a molecular weight of about 4,500.
Sample J of Table 6 and the control examples including the
commercial cleaners received as concentrates were diluted
(10.times.) with water and the solutions heated to 160.degree.
F.
A soil mix was made of 1/3 part heavy oils and greases taken from
the bottoms of a petroleum distillate, 1/3 part used motor oil and
1/3 part axle grease. Approximately 1 gram of the mixed soil was
applied to a metal mesh screen. The metal mesh screen was immersed
in the heated cleaning solutions and periodically taken from these
solutions and weighed to determine the amount of soil removal. The
results are shown in the Figure in which each of the data points
represents the mean of three measurements.
As can be seen from the Figure, the aqueous cleaner of the present
invention yielded substantially improved results after the first
minute of cleaning, compared with the alkaline control and the two
commercial products.
EXAMPLE 4
In a typical commercial use of the metal cleaning compositions of
the present invention, the cleaning solution is continuously
filtered to remove solid contaminants or separate a contaminant
phase and then recycled for reuse. Upon continual reuse, the
cleaning solution will contain an increased amount of contaminants
which are contained within the cleaning solution. It is useful that
a commercial cleaning composition still be able to clean upon
repeated usage of the solution even though the composition contains
a significant amount of the contaminants which have been removed
from the surface. This example illustrates the useability of the
cleaning composition of the present invention.
In this Example, the formulation Sample J which is set forth in
Table 6 above was tested to determine its ability to clean after
repeated treatments to remove contaminants therefrom.
A soil mix was made of 1/3 part heavy oils and greases taken from
the bottoms of a petroleum distillate, 1/3 part used motor oil and
1/3 part axle grease. Approximately 1 gram of the mixed soil was
applied to a metal mesh screen.
100 ml of the concentrate (Sample J) set forth in Table 6 was
diluted (10.times.) to 1000 ml with tap water and heated to about
160.degree. F. The metal mesh screen was immersed in the heated
cleaning solution for approximately 3 to 4 min. and taken from the
solution for weighing to determine the amount of soil removal. The
oil remaining on the mesh represents the "initial oil remaining"
set forth in Table 7 below.
64 grams of an oil and 135 grams of a greasy bottoms obtained from
cleaning metal parts was added to the heated test solution. The
amount of contaminants added to the solution represents
approximately 4-6 weeks of heavy cleaning. The metal mesh was again
immersed in the solution for 3-4 min., removed and weighed to
determine the amount of oil still present on the mesh. This
represents the "final oil remaining" as set forth in Table 7
below.
The solution was allowed to cool to room temperature and the top
oil layer was removed. The solution was then filtered through
Celite.TM.. The treated solution was then recorded for weight, pH,
and conductance. Makeup solution was then added based on a 1/10
dilution with tap water to 1000 ml and heated to working
temperature. The above represents one cleaning cycle. Six of such
cleaning cycles were repeated and the results of cleaning are set
forth in Table 7 below.
TABLE 7 ______________________________________ solution Initial Oil
Final oil milli- solution cycle # remaining remaining siemens pH
______________________________________ 1 8% 60% 15.4 9.2 2 5% 56%
24.4 9.4 3 9% 64% 25.8 9.2 4 7% 71% 30.6 9.4 5 5% 72% 34.2 9.2 6 8%
37% 36 9.3 ______________________________________
The addition of the oil tops and residue bottoms to the cleaning
solution for each cycle was meant to simulate approximately 20-30
weeks of cleaning. As can be seen, the solution was able to
maintain its cleaning ability throughout the test.
EXAMPLE 5
Sample K represents a particularly useful concentrated formulation
in accordance with this invention.
TABLE 8 ______________________________________ SAMPLE K wt %
______________________________________ Deionized water 79.58 Sodium
bicarbonate 4.480 Potassium carbonate 2.900 Sodium carbonate 2.220
Magnesium oxide 0.074 Carboxylated Polymer.sup.1 0.250 Sodium
nonanoate 6.000 Alcodet 260 3.000 LP 100 1.500
______________________________________ .sup.1 Acrylic acid/maleic
anhydride copolymer molecular weight of about 4,500.
* * * * *